Typical multi-layered vacuum super insulated cryogenic tanks utilize a pair of cylindrical inner and outer tanks that are arranged concentrically with the inner tank residing in an interior of the outer tank. There are multiple radiant heat shields (insulation layers), approximately 30-80, coiled around the inner tank between the inner and outer tanks. A high vacuum exists between the inner and outer tanks to further prevent heat transfer. This type of thermal insulation is called a multi-layered vacuum super insulation. These storage tanks are capable of storing fluids at cryogenic temperatures.
The inner tank is positioned within the outer tank so that the inner tank does not contact the outer tank and so that thermal conduction paths between the inner and outer tanks are minimized. The fluid is supplied to and removed from the inner tank through a plurality of discrete fluid lines that extend through the outer tank, the vacuum between the inner and outer tanks, and into the inner tank at separate locations. Each of these fluid lines is a conductive heat path that can result in parasitic heat leaks into the inner tank.
The fluid lines are typically of a double wall construction inside the inner tank with a vacuum insulation therebetween to reduce the parasitic heat leaks into the inner tank. The double wall vacuum insulation shares the vacuum with the gap between the inner and outer tanks. The double wall fluid lines inside the inner tank typically have long horizontal runs and one or more bends or changes in direction. This construction has various drawbacks. The bending of the multiple double wall fluid lines is difficult and time consuming. Additionally, the use of discrete double wall fluid lines results in multiple obstructions in the wrapping of the insulation layers around the exterior of the inner tank. The insulation layers need to be cut for each of these obstructions. Each of these cuts/breaks in the insulation layers results in a potential thermal shortcut for a parasitic heat leak into the inner tank. Furthermore, the cutting of the insulation layers is time consuming and makes automated production difficult. Moreover, the long horizontal runs may develop a homogenous temperature profile and lead to additional parasitic heat leaks through natural convection. Thus, it would be advantageous to provide a storage tank that reduces or minimizes these drawbacks.